The present invention relates to a cone clutch especially suitable for a transmission selectively shiftable to a forward position and reverse position of a small boat.
A conventional mechanism is detailed below with reference to FIG. 1. In FIG. 1, an input shaft 2 and an output shaft 3 are carried parallel to each other in a case 1. The output shaft 3 rotatably supports a pair of cone cups 5 respectively having inner peripheral faces 4 of conical shape. The cone cups 5 are respectively provided at the outer peripheries with teeth 6 meshing with teeth 7 provided at the outer peripheries of the input shaft 2. The teeth 6 of the one cup 5 directly mesh with the teeth 7, and the teeth 6 of the other cup 5 mesh with the teeth 7 through an idle gear (not shown). A cone body 9 is supported on the output shaft 3 slidably through a helical spline 10. The cone body 9 is located between the cone cups 5 and is provided with conical outer peripheral faces 8 which face and are engageable to the conical inner periphral faces 4. The cone body 9 is provided at the outer peripheral surface with an annular groove into which a shift fork (not shown) engages. The shift fork is operable to axially shift the cone body 9 to press and frictionally engage the face 8 to the face 4 selectively.
The inclination of the spline 10 is so determined that the cone body 9 may be forced toward the corresponding cone cup 5 when the body 9 is pressed to the cup 5 to receive a rotational force. Namely, the helical spline 10 functions to press the cone body 9 against the cone cup 5 by the force corresponding to the transmitted torque.
However, according to the above conventional structure, the fluctuation of the transmitted torque causes a fluctuation of the above pressing force for the engagement. Especially, in a low speed area of a Diesel engine, the torque largely fluctuates, so that the the cone body 9 sometimes slips on or disengage from the cup 5. This promotes the wear of the faces 4 and 8 for the frictional engagement and may interrupt the engagement.
A structure overcoming the above problem is disclosed in the Japanese patent application No. 57-34516 corresponding to the Swedish patent application No. 8101424-3. According to the first embodiment of the above Japanese application, an intermediate shaft carrying a cone body is slidable with respect to input cone cups and is forced by springs, so that the axial movement of the intermediate shaft may absorb the fluctuation of the pressing force for the engagement.
However, in this structure, the intermediate shaft should be constructed slidable, which causes a problem that the construction is complicated.
In other embodiments of the above application, a cone body is divided into two portions, one of which is connected to a shaft, and the others are designed to be pressed to cone cups. Springs are disposed between both portions of the cone body. This structure also has complicated constructions. Further, since the cone body is generally made of soft material such as brass or bronze, these divided portions spline together may not have a sufficient strength.
Further, in both of the above embodiments, since it is necessary to use the slidable shaft or the divided cone body, they have another problem that the conventional shaft 3 and the cone body 9 in FIG. 1 can not be used in the structures of those embodiments.
Accordingly, it is an object of the invention to provide a cone clutch having simple constructions and operable to absorb a fluctuation of a pressing force for an engagement caused by a fluctuation of a toque.
According to the invention, a cone clutch comprises a rotation shaft which is axially unslidable; a cone body which is connected to the rotation shaft through a spline, is operable to be axially shifted by a shift means, and is provided at the outer periphery with a pair of conical friction faces; a pair of cone cups which is carried on the rotation shaft rotatably and slidably in the direction opposite to the cone body, and has conical friction faces operable to be pressed to above conical friction faces, respectively; a force transmission means for trnsmitting a rotation force to both cone cups respectively in directions opposite to each other; and force means for forcing the near faces of the respective cone cups toward the cone body.
Other and further objects, features and advantages of the invention will appear more fully from the following description of the preferred embodiments of the invention.